The concept of relieving or preventing pain by the application of cold devices is commonplace. The device comprising this invention takes this proven and widely-used pain-alleviating technique and applies it to a hypodermic syringe assembly. One routine application of cold to achieve a local anesthestic effect is the use of ethyl chloride. This rapidly-evaporating chemical is sprayed on the surface of the skin to anesthetize a small area so that minor surgery operations may be performed comfortably. Such operations are performed in this manner to remove, for example, a wart, mole, or other skin growth.
The device comprising the invention does not freeze the skin but lowers the surface temperature of the skin sufficiently to act as an effective local anesthetic for needle insertion. Further, the cold is continually applied to the site during needle insertion and injection and therefore, the anesthetic effect of the cold is maintained throughout the procedure for a sufficient period of time. This is not the situation when using ethyl chloride which continues to warm once it has been applied, thereby reducing its anesthetic effects.